Tiltable bearing, especially for bridges

ABSTRACT

The present tiltable bearing for heavy structures such as bridges has a load supporting piston which extends into a space confining pot into which is inserted a yielding pressure material, such as a rubber cushion, on which the piston rests. For preventing the escape of the cushion material through the gap between the outer piston walls and the inner walls of the pot, there is provided a sealing body of material which is more rigid than the cushion material. The sealing body faces said gap and forms an integral structure with the gap.

United States Patent [191 Koester et .al.

[4 1 Jan. 1,1974

[ TILTABLE BEARING, ESPECIALLY FOR BRIDGES [75] Inventors: WaldemarKoester, Forsbach,

Germany; Reinhold Huber, Rorbas, Switzerland [73] Assignee: Kober AG,Glarus, Switzerland [22] Filed: Dec. 21, 1971 [21] Appl. No.: 210,493

[30] Foreign Application Priority Data Dec. 24, 1970 Germany P 20 63746.1 Mar. 25, 1971 Germany P 21 14 391.9

[52] US. Cl. 308/3 R, 14/16 [51] Int. Cl. F16c 27/06 [58] Field ofSearch 308/3 R; 277/188; 14/16 [56] References Cited UNITED STATESPATENTS 3,491,392 1/1970 Waller 14/16 2,386,873 10/1945 Mercier 277/1883,094,337 6/1963 Pippert et a1. 277/188 3,521,893 7/1970 Josephson277/188 FOREIGN PATENTS OR APPLICATIONS 206,777 8/1966 Sweden .,14/161,202,813 10/1965 Germany ..14/16 Primary ExaminerAl Lawrence SmithAssistant ExaminerBarry Grossman AttorneyWo1fgang G. Fasse [57] ABSTRACTThe present tiltable bearing for heavy structures such as bridges has aload supporting piston which extends into a space confining pot intowhich is inserted a yielding pressure material, such as a rubbercushion, on which the piston rests. For preventing the escape of thecushion material through the gap between the outer piston walls and theinner walls of the pot, there is provided a sealing body of materialwhich is more rigid than the cushion material. The sealing body facessaid gap and forms an integral structure with the gap.

7 Claims, 5 Drawing Figures TILTABLE BEARING, ESPECIALLY FOR BRIDGESBACKGROUND OF THE INVENTION The invention relates to tiltable bearings,especially for bridges or similar supporting structures wherein a pistonis inserted into a preferably cylindrical pot or housing to rest on acushion of yielding pressure mate rial such as rubber. Such bearingsusually include at least one sealing body arranged in front of the gapbetween the pison and the inner surface of the housing wall. The sealingbody is made of a material having a greater strength or rigidity thanthat of the cushion.

In a known tiltable bearing of this type the gap between the piston anthe inner surface of the housing is sealed by a sealing ring which ismade of a synthetic material having a low coefficient of friction andwhich is embedded in' the cushion or'pressure material in the manner ofa piston ring. Due to such piston ring-like construction of the sealingring, abrasive wear and tear occurs between the sealing ring and thecushion. Another drawback of this prior art bearing is seen in thatduringv the production of the sealing ring and cushion tolerances forfitting these parts together must be observed. See German PatentPublication DAS No. l 202 813.

Another disadvantage of this known arrangement is seen in the wear andtear to which the cushion is subjected especially around itscircumference. Due to the tilting: movements transmitted'to the pressurecushion the latter is subjected to compressions and expansions wherebyespecially the circumferential surface of the softer pressure cushionmaterial is subject to said wear and tear which is of an abrasivenature.

OBJECTS OF THE INVENTION SUMMARY OF THE INVENTION According to theinvention there is provided a tiltable bearing, especially for bridgesor similar supporting structures, having a piston extending into ahousing having a bottom and side walls with the gap between the pistonand said side walls of the housing, said piston being supported on apressure cushion of yielding material confined between the housing andthe piston, said bearing including at least one sealing body adjacent tosaid gap, wherein said sealing body is made of a material which is morerigid than the pressure material, and wherein the sealing body and thepressure cushion form an integral structure.

The cushion and sealing body may be produced initially as a one piecestructure whereby the differences in the material characteristicsbetween the cushion proper and the sealing body may be produced by anafter treatment or after treatment steps. However, it is also possibleto first produce the cushion and the sealing body as separate elementsand to them unite these elements with each other, for example by gluingor welding. Furthermore, one element may be produced first while theother is then formed onto the first element during its production, forexample by vulcanization.

Uniting the sealing body and cushion in accordance with the presentinvention, makes it unnecessary to observe production tolerances forfitting these elements together. Also the assembly is simplified sinceit is no longer necessary to insert the sealing ring into a groove inthe pressure cushion.

BRIEF FIGURE DESCRIPTION In order that the invention may be clearlyunderstood, it will now be described, by way of example, with referenceto the accompanying drawings, wherein:

FIG. 1 is a cross section through a tiltable bearing with a cornersealing body, in accordance with the present invention, wherein thecorner sealing body or ring has a triangular cross section;

1 FIG. 2 is a partial cross section through a tiltable bearing similarto that of FIG. 1, wherein the sealing ring has a modified crosssectional shape;

FIG. 3 is a cross section similar to that of FIG. 1, wherein the sealingbody envelopes the peripheral surface of the pressure cushion;

FIG. 4 is a partial cross section through a tiltable bearing similar tothat of FIG. 3, wherein a modified sealing body envelopes the peripheralsurface of the pressure cushion; and

FIG. 5 is a partial cross-section through a tiltable bearing withsealing rings inserted into peripheral regions of the pressure cushion.

DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION The tiltable bearingshown in FIG. 1 comprises a housing or pot 3, preferably of cylindricalshape, arranged to rest on a supporting structure 2, such as a concretefoundation and to support a bridge member 1 through a piston 5 insertedinto the housing 3 and resting on a pressure materialforming a pressurecushion 4 made of an elastically or plastically'yielding pressure mass,such as rubber or plastics material, enclosed within pot 3. The pressurecushion 4 is compressed by the piston 5' which extends partly into pot3. In order to prevent the escape of the pressure mass through the gapbetween the piston 5 and the pot 3 an annular sealing body 6 is embeddedin the pressure cushion which seals the gap and which is united with thepressure cushion to form a unitary, one-piece or integral structure. Asshown, the sealing body 6 forms the upper circumferential corner of thepressure cushion 4 extending all around the pressure cushion.

The material of the sealing body 6 must be such that it maintains itsshape in front of the gap to be sealed. Moreover, it has to besufficiently elastic to follow the expansion movements of the bearingelements as well as take up the displacements or shifting occuringduring tilting. In addition, it should yield to the pressure of thepressure mass of the cushion to the extent that the sealing body closelyengages the adjacent portions of housing 3 and of the piston 5.

A pressure cushion of the invention including a onepiece sealing bodymay preferably be manufactured as follows:

a. a strip of a rubber mass capable of developing a greater Shorehardness than the pressure cushion itself, is placed into the bottomcorner of a mold for the rubber cushion to form a ring;

b. then the remainder of the mold is filled with a rubber mass capableof developing a lower Shore hardness than said ring;

0. the entire content of the mold is then vulcanized;

d. after removal from the mold, a unitary pressure cushion is obtainedthe rim of which forms a sealing body with the necessary hardness forsealing the gap and the remainder of which is softer.

Instead of producing the two different degrees of hardness between thecushion proper and the sealing ring, it is also possible to let thehardness of the sealing body change in several steps, preferablygradually toward the hardness of the material of the pressure cushion.Stated differently, the sealing ring hardness may diminish graduallyfrom its outer surface toward the pressure cushion.

As an alternative possibility, the bonding between the material of thesealing body and the material of the pressure cushion may also beaccomplished by gluing, for example by a rubber cement.

The above statements regarding the embodiment shown in FIG. 1 also applycorrespondingly to the other embodiments described herein.

It is to be understood that although in FIG. 1 the side or face 7,forming the transition from the rim or corner zone to the soft pressurecushion is plane, it may be curved, for example it may be convex orconcave. This transition face may also have a rectangular or trapezoidalcross section.

FIG. 2 shows a cross section through another embodiment of the rim orcorner zone of a pressure cushion. More specifically, the cross sectionof FIG. 2 shows on a somewhat enlarged scale, as compared to FIG. 1, aportion corresponding about to the portion encircled by a dash-dottedline A" in FIG. 1. In FIG. 2, the sealing body in the corner zone of thepressure cushion in front of the gap has an angular cross section. Areinforcement means may preferably be employed directly in the cornerregion of the sealing body. Thus, for example, wires 8 of metal orsynthetic material are embedded in the sealing body to provide saidreinforcement. These wires preferably extend all around inside thesealing body. A single reinforcing wire ring or the like may also beembedded in the corner area of the sealing body.

If the pressure cushion and the sealing body are made of differentmaterials, the materials will 'be selected so as to assure a veryintimate and solid or strong bond between the two materials of thesealing body and cushion. It is desirable that the two materials enterinto a latice-like polymerization in the transitional zone between thesealing body and the pressure cushion. This transitional zone is notsharply delimited since the polymerization forms three dimensional chainlinks of the interconnected materials due to the immediate union ofmolecule chains reacting with each other.

Another embodiment of the invention is shown in FIG. 3, wherein thesealing body 6 is formed as an envelope 12 covering substantially theentire circumferential surface of the pressure cushion 4. Since theenvelope 12 is made of a stronger or more rigid material as compared tothat of the pressure cushion, abrasive wear and tear is effectivelyprevented. In selecting the material for the envelope, care should betaken that it not only will maintain its shape with respect to the gapto be sealed but that it also has a good sliding property relative tothe inner wall of the housing 3. In addition, the material of theenvelope 12 has to be at least vertically elastically deformable inorder not to impede the tilting movement within the permissable limits,besides, the envelope material must be resistant to abrasion. As in theother embodiments, the advantage is again that wear and tear betweenpressure cushion and the envelope are eliminated due to the presentintegral structure.

The sealing body in the form of a casing or envelope for the pressurecushion may also have many different shapes. A very good bond betweenthe casing or envelope and the pressure cushion is obtained bybroadening the envelope along the bottom of the housing or by providingthe casing with teeth along the side facing the softer pressure cushion.Especially good pressure conditions result when the casing has a concaveinner shape which encircles a respective convex outer circumference ofthe pressure cushion as shown in FIG. 3. However, other cross sectionalshapes of the envelope may be selected and serve efficiently for sealingthe gap between the piston and the housing. Thus, the envelope may havea U-shaped, serrated, meandering (FIG. 4) or similar configuration.

Referring more particularly to FIG. 3, the sealing envelope 12 for thepressure cushion 4 extends substantially along the inner circumferentialsurface 13 of the housing 3. The top and bottom region of the envelope12 is wider opposite the gap to be sealed and at the bottom 14 ofhousing 3 than the remainder of the envelope. This improves the sealingfunction of the casing or envelope and prevents that the softer mass ofthe pressure cushion 4 comes into contact with the inner surface of thehousing 3. In FIG. 3, the enveloping sealing body 12 has a concaveinwardly facing surface whereby its cross section has a shape somewhatas a sickle. As mentioned above, other cross sectional shapes may beused, for instance a rectangular shape.

The selected cross sectional shape of the sealing body depends in parton the strength of the bond between the sealing body material and thepressure cushion material.

FIGS. 4 and 5 show modifications of the tiltable bearing of FIG. 3 whichdiffer from the latter in the configuration of the sealing body. FIGS. 4and 5 show on a somewhat enlarged scale a portion corresponding to thatencircled in FIG. 3 by a dash-dotted line B. More specifically, in FIG.4, the face 9 of the sealing body 12a which faces the softer pressurecushion 4 is wavy or meandering. As mentioned above, other shapes couldbe used, for the sealing body, thus it could be serrated, U-shaped orstepped.

Referring to FIG. 5, this embodiment comprises a plurality of sealingrings 11 embedded in the circumference of the pressure cushion 4 spacedat intervals from each other and having a ring shape. This embodimentalso prevents substantially abrasive wear of the pressure cushion at itscircumference since the harder material of the rings 11 supports thesofter pressure cushion material between the rings 11, though thecushion may contact the inner surface 13 of the housing 3 between therings 11, however, this is not an intimate contact because the sealingrings 11 of harder material resting against the inner surface 13 preventsuch a contact and thus limit the wear of the pressure cushion.

Referring further to FIG. 5, it is within the present teaching that therings 1 1 of the sealing body may form a spiral embedded in the pressurecushion, whereby the spiral preferably forms at each of its ends aclosed ring resting on one side against the inner surface of the bottom14 of the housing 3.

The one piece or integral structure of one or more sealing bodies withthe pressure cushion may be obtained as mentioned, by an after-treatmentof a pressure material which prior to such treatment was one and thesame material for the cushion proper and the sealing ring. Suchafter-treatment may, for example, involve a localized vulcanization ifthe starting material is, for instance, synthetic rubber, wherebylocalized regions of greater Shore hardness may be obtained for thesealing ring areas as compared to the Shore hardness of material of thepressure cushion.

As briefly indicated above, the pressure cushion and sealing bodies may,however, also be made of different materials and may be interconnectedby gluing or by an intimate bond such as is obtained, for instance, byvulcanizing or welding. Material combinations which are capable ofentering into an interlace bond or polymerization with each other orotherwise enter into an intimate bond may be used successfully such assynthetic materials, plastics, rubber,Neoprene," Vulkollan or syntheticmaterials having similar properties. Catalysts or glues may be used toaccelerate the hardening of the synthetic material to assure said bondbetween the two materials along the interface thereof.

In view of the foregoing it is to be understood that the inventioncomprises all modifications and equivalents within the scope of theappended claims.

What is claimed is:

1. In a tiltable bearing wherein a supporting piston rests with itsbottom surface on a yielding cushion of pressure material in a housing,wherein a gap is formed between a circumferential piston surface and aninner circumferential surface of the housing walls, wherein sealingmeans are located between the pressure material and said gap, saidyielding cushion and said sealing means forming an integral structure,said sealing means having a mechanical strength larger than that of saidpressure material of the yielding cushion, the improvement wherein saidyielding cushion has a top and bottom surface and a circumferential ringsurface interconnecting said top and bottom surfaces, said sealing meansforming a continuous ring zone which covers the entire circumferentialring surface of the yielding cushion, said continuous ring zone havingsaid larger mechanical strength, said continuous ring zone providing agood sliding property relative to the inner wall of the housing, andmeans for initially bonding said mechanically stronger ring zone to theentire circumferential ring surface of said cushion whereby said ringzone sub stantially insulates the yielding movements of said clishionfrom said inner housing walls while simultaneously providing reducedfriction between the ring zone and said inner housing walls.

2. The tiltable bearing according to claim 1, wherein said ring zone hasa concave inner surface intimately bonded to the ring surface of theyielding cushion.

3. The tiltable bearing according to claim 1, wherein said ring zone hasa corrugated inner surface which grips into a respective corrugation ofthe circumferential ring surface of the cushion.

4. The tiltable bearing according to claim l, wherein the sealing ringzone is of the same material as the yielding cushion.

5. The tiltable bearing according to claim 1, wherein the means forintimately bonding comprise glue or a vulcanized or a welded interfacebetween the cushion and the sealing ring zone.

6. The tiltable bearing according to claim 1, wherein the sealing meansand the yielding cushion are made of different materials capable ofintimately bonding to each other.

7. The tiltable bearing according to claim 1, wherein the sealing meansand the yielding cushion are made of materials of the natural orsynthetic rubber type.

1. In a tiltable bearing wherein a supporting piston rests with itsbottom surface on a yielding cushion of pressure material in a housing,wherein a gap is formed between a circumferential piston surface and aninner circumferential surface of the housing walls, wherein sealingmeans are located between the pressure material and said gap, saidyielding cushion and said sealing means forming an integral structure,said sealing means having a mechanical strength larger than that of saidpressure material of the yielding cushion, the improvement wherein saidyielding cushion has a top and bottom surface and a circumferential ringsurface interconnecting said top and bottom surfaces, said sealing meansforming a continuous ring zone which covers the entire circumferentialring surface of the yielding cushion, said continuous ring zone havingsaid larger mechanical strength, said continuous ring zone providing agood sliding property relative to the inner wall of the housing, andmeans for initially bonding said mechanically stronger ring zone to theentire circumferential ring surface of said cushion whereby said ringzone substantially insulates the yielding movements of said cushion fromsaid inner housing walls while simultaneously providing reduced frictionbetween the ring zone and said inner housing walls.
 2. The tiltablebearing according to claim 1, wherein said ring zone has a concave innersurface intimately bonded to the ring surface of the yielding cushion.3. The tiltable bearing according to claim 1, wherein said ring zone hasa corrugated inner surface which grips into a respective corrugation ofthe circumferential ring surface of the cushion.
 4. The tiltable bearingaccording to claim 1, wherein the sealing ring zone is of the samematerial as the yielding cushion.
 5. The tiltable bearing according toclaim 1, wherein the means for intimately bonding comprise glue or avulcanized or a welded interface between the cushion and the sealingring zone.
 6. The tiltable bearing according to claim 1, wherein thesealing means and the yielding cushion are made of different materialscapable of intimately bonding to each other.
 7. The tiltable bearingaccording to claim 1, wherein the sealing means and the yielding cushionare made of materials of the natural or synthetic rubber type.